The present invention relates to coffee servers in general. More specifically to a process for manufacturing stainless steel coffee servers to provide communication between vacuum insulated separated walls, using furnace brazing techniques while maintaining structural integrity of the handle connection.
Previously, many types of coffee servers have been used in endeavoring to provide an effective means to insulate the server using negative pressure as the insulating media. Hitherto the usual manufacturing process used by prior art has been to use vacuum insulation only between the vertical walls, as structural connection for the handle is difficult to achieve if a full vacuum insulation is used completely around the vessel when it is necessary to maintain a connection to the interior of the server.
A search of the prior art did not disclose any patents that possess any of the novelty of the instant invention, however the following U.S. patents are considered related:
Letsch et al. in U.S. Pat. No. 4,754,888 discloses a carafe with an inner container surrounded by a casing. The inner container and the casing have an opening at the top which may be closed by a separate plug. The plug and opening in the container and casing are shaped such that it is possible to fill or empty the inner container while the plug is still in the opening. The plug and container both have mating grooves that provide opposed flow paths into and out of the container. The container also includes a basin around the top for receiving coffee from a coffee maker and the plug has openings to provide a flow path from the basin into the container interior.
Karp in U.S. Pat. No. 5,249,703 teaches a travel mug that includes a container and a lid in combination. The container has a handle and an annular lip that has an annulus capable of forming a seal with the top side of the annular lip. A cylindrical well in the lid has a vertical dividing wall such that the lid may be readily rotated by hand. The retaining arms extend from the underside of the lid and engage the underside of the annular lip to pull it into tight abutment. Diametrically opposed gaps in the lip act as passageway for the retaining arms. Similarly diametrically opposed notches in the lid align with the gaps to allow liquid to be poured from the container.
U.S. Pat. No. 5,918,761 issued to Wissinger is for an insulated container and cover combination that has an outer container shell terminating at an opening with a surrounding edge. An inner container shell is nested within the outer container shell and has an opening surrounded by a continuous edges in abutment with the surrounding edge. The inner container shell is spaced inwardly and is out of contact with the outer shell. A cover mounting assembly is attached to the outer shell adjacent to the opening. A single seal, made of elastomeric material, has a sealing surface disposed at the interface of the shells. Locating rings define the removable cover mounting assembly and locate the single sealing ring on the inner and outer shells.
For background purposes and as indicative of the art to which the invention is related reference may be made to the remaining cited design patents.
Heretofore the art of manufacturing stainless steel coffee servers and other liquid containers that employ vacuum as a thermal barrier for insulation have been limited to the so called double walled type as there has been no successful method of penetrating both sides of the shells simultaneously. Furthermore it is particularly important to indicate how much coffee remains inside the server as the stainless steel construction renders the liquid volume within the interior concealed and out of sight. A liquid level sight gauge has been developed that is housed inside the handle and visually indicates the level through a transparent tube, however the problem of how to attach the handle and provide an opening to the interior and still utilize the vacuum furnace type of construction has prevailed.
It is therefore a primary object of the invention to solve this dual problem by providing a strong robust handle mounting device using a hollow threaded coupling inserted into a hole in both the inside and outside walls of the server and adding a mixture of brazing powder and flux around the interface of the coupling to the holes. When the server is placed in a vacuum furnace, initially evacuated and heated, the brazing compound melts and through capillary action encircles the interface and permanently joins the stainless steel walls to the coupling. Since the coupling is permanently and rigidly attached to both walls, the handle has a solid fixed member to grip against and the transparent tube to indicate liquid level may be easily attached to the couplings open end, forming a conduit for the liquid.
Another difficulty has arisen in the techniques of manufacturing stainless steel coffee servers and other liquid containers that employ vacuum as a thermal barrier has been in the spacing of a base to the outer shell in an accurate and repeatable manner. While this connection is simple by itself the problem is compounded by the need to create a precise welding gap therebetween permitting the height of the server to be controlled and the gap regulated.
To solve this problem an important object of the invention has been realized by simply placing a ceramic ring in between the base and inner liner when positioning them together. This ring acts as a spacer eliminating the need for expensive and elaborate jigs and fixtures to retain the elements separation. Further the ring, being ceramic, may permanently remain in this position without any difficulty as it has a low coefficient of heat transfer and is held in place by compression between the two components since they are held in position by gravity during the welding procedure. It should be noted that this novel addition to the assembly operation produces the proper welding gap regardless of the tolerance build up of the mating elements as the deep drawing procedures and cut off techniques may not always lend themselves to precision dimensional tolerances and excessive gap or misalignment between the elements could lead to voids in the weld seam.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.